The present invention relates to a method for producing a spinning nozzle plate having nozzle capillaries.
When fibers of organic or inorganic material are produced in large-scale industrial systems, the starting material is pressed, in a flowable state, through spinning nozzle plates which are equipped with a plurality of spinning nozzle channels. In most cases, the spinning nozzle channels are composed of nozzle capillaries through which the material to be spun is discharged and a significantly wider preliminary channel into which the material to be spun is fed. The preliminary channels are generally cylindrical or funnelshaped, and can be produced relatively easily by drilling or piercing. The nozzle capillaries may have profiles of a special shape (for example, star-shaped cross sections) and require more complicated techniques, e.g. wire erosion or erosive countersinking. Nozzle capillaries with specially shaped, non-circular cross sections will hereafter be deemed "profiled" nozzle capillaries.
Spinning nozzle plates are parts which are subject to wear. Spinning nozzle plates having profiled nozzle capillaries, in particular, constitute a considerable cost factor during production of fiber products when the plates are produced in the prior art manner. Moreover, in the prior art manner of manufacturing profiled nozzle capillaries, the lower critical dimension limit that can be realized with justifiable expenditures generally lies at about 30 .mu.m. This limits the configuration of the filaments that can be produced.